© Cengage Learning 2015

5.8 How Do Large Particles/Bulk Substances Move Across Membranes?

• Vesicle movement– Exocytosis: cell expels a vesicle’s contents to extracellular fluid– Endocytosis: cell takes in a small amount of extracellular fluid

(and its contents) by the ballooning inward of the plasma membrane

– Phagocytosis: “Cell eating”; an endocytic pathway by which a cell engulfs particles such as microbes or cellular debris

© Cengage Learning 2015

Membrane Trafficking

• Membrane proteins and lipids are made in the ER and move to the Golgi bodies for final modification– “Finalized” vesicles containing proteins and lipids move to and

fuse with the plasma membrane

• Exocytosis and endocytosis continually replace and withdraw membrane patches